Problems Pinging VM from Another VM

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I have 2 virtual machines that can not ping/access one another.
I am setting up a exchange server, and a domain controller as guest machines in virtualbox. All machines including the host are running windows server Datacenter 2008 R2. I have my networking set to "bridged", and static ip's set in both the virtual machines, and host (but not on the network adapters). Both machines can be pinged from the outside, and can ping the outside. The machines are both on the same ip subnet. The host can ping both virtual machines as well.
Summary:
servers can ping everything but the other VM
Networki
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